1. Field of the Invention
The invention relates to a precompression pump for the spraying under pressure of a liquid, and in particular, of a cosmetic product such as a hair lacquer. The invention aims, in particular, to provide a pump of this kind that is operable by hand and of a small size, so that it can be accommodated in the cover cap of a dispenser for liquids.
2. Description of the Related Art
It is known that the precompression of a liquid contained in the body of a pump can ensure a good spraying quality irrespective of the mode of actuating the pump, and one therefore tries to obtain adequate precompression. Moreover, to maximize precompression efficiency, it is necessary that the loss of pressure during the flow of the liquid from the pumping chamber to the spraying nozzle should be as low as possible.
From Applicant's EP-A 0 437 131 there is known a manual precompression pump comprising, inter alia, a chamber for pumping the liquid that is in communication with a precompression chamber, a spraying nozzle connected by a dispensing duct to the precompression chamber, and a feeder duct provided with a non-return valve leading into the pumping chamber.
The precompression pump of the kind described in the EP-A 0 437 131 has low spraying accuracy because the actuation of this pump is effected by pressing on a push button which includes the spraying nozzle. As a result, it is difficult to target the spot where the spray is to be applied.
Moreover, because of its design, this known pump is difficult to assemble. Indeed, since all the parts making up this pump are aligned on the same axis of symmetry, its size in the axial direction is relatively large, which prohibits its use in many applications using a cover cap.
FR-A-2 634 825 discloses a precompression pump for the pressurized spraying of a liquid. There, a cylindrical body defines a cylindrical pumping chamber. A first piston, or actuating piston, associated with a manipulating element is accommodated in the pumping chamber, this piston bearing against a first resilient restoring means disposed in this chamber. A cylindrical precompression chamber communicating with the pumping chamber is provided with a second piston, or precompression piston, bearing against a second resilient restoring means. A feeder duct is provided with a non-return valve leading into the pumping chamber. A dispensing element is provided with a spraying nozzle and a dispensing duct connects the nozzle to the precompression chamber. The precompression chamber has a sliding means for providing the connection and closure of the dispensing duct, so that the connection is interrupted in the rest position of the pump. This connection is established at the end of the precompression under the action of the manipulating element. The sliding means for providing the connection and closure then frees a passageway between the precompression chamber and the dispensing duct.
This pump has the drawback of requiring a large number of components. Moreover, it is difficult to assemble in an industrial environment. The cost of such a pump is therefore relatively high. Moreover, the connection between the pumping chamber and the precompression chamber is constituted by a relatively long duct having several angles. Because of this, a loss of pressure occurs in the liquid during its dispensing, resulting in a spray of poor quality. Furthermore, the need for a one-way valve in this duct increases the pressure loss still further, thus requiring a considerable force on the user's part for actuating this pump. Finally, this pump has a large bulk, so that its use cannot be envisaged for all the requirements, in particular for the dispensing of liquids contained in containers with a small capacity.